"No march has been authorised by the ministry of the interior," Tarrouche said, adding that "the law will be applied against all acts of violence... Some calls for violence are circulating on Facebook." Several wings of the ultra-conservative Salafist movement have during the week issued calls to demonstrate after Friday prayers to denounce "attacks on sacred values", in the wake of a controversial art exhibition.

Works considered "blasphemous" and offensive to Islam were destroyed last Sunday at the exhibition in northern Tunis in an act blamed on Salafists.

The incident sparked clashes across the north African country between Monday and Wednesday that saw police stations and political party offices torched, in the worst violence since the January 2011 revolution.

One person was killed and more than 100 injured, including 65 policemen.

The Islamist movement Ennahda, which dominates the government and the national assembly, called Wednesday for "a peaceful march to defend the revolution and sacred values".